Liquid-crystalline medium

ABSTRACT

The invention relates to a liquid crystalline medium, characterised in that it comprises one or more compounds of formula A 
                         
and
 
one or more compounds of formula II
 
                         
wherein the parameters have the meaning indicated in claim  1 , and to high-frequency components comprising the same, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, in particular microwave phased-array antennas.

The present invention relates to liquid-crystalline media and tohigh-frequency components comprising the same, especially microwavecomponents for high-frequency devices, such as devices for shifting thephase of microwaves, in particular microwave phased-array antennas.

Liquid-crystalline media have been used for decades in electro-opticaldisplays (liquid crystal displays—LCDs) for the purpose of informationdisplay. A different application developed more recently is their use incomponents for microwave technology, such as, for example, disclosed inDE 10 2004 029 429 A and in JP 2005-120208 (A).

As a typical microwave application, the concept of the invertedmicrostrip line as described by K. C. Gupta, R. Garg, I. Bahl and P.Bhartia: Microstrip Lines and Slotlines, 2^(nd) ed., Artech House,Boston, 1996, is employed, for example, in D. Dolfi, M. Labeyrie, P.Joffre and J. P. Huignard: Liquid Crystal Microwave Phase Shifter.Electronics Letters, Vol. 29, No. 10, pp. 926-928, May 1993; N. Martin,N. Tentillier, P. Laurent, B. Splingart, F. Huert, P H. Gelin, C.Legrand: Electrically Microwave Tunable Components Using LiquidCrystals. 32^(nd) European Microwave Conference, pp. 393-396, Milan2002; or in Weil, C.: Passiv steuerbare Mikrowellenphasenschieber aufder Basis nichtlinearer Dielektrika [Passively Controllable MicrowavePhase Shifters based on Nonlinear Dielectrics], DarmstädterDissertationen D17, 2002; C. Weil, G. Lüssem, and R. Jakoby: TunableInvert-Microstrip Phase Shifter Device Using Nematic Liquid Crystals,IEEE MTTS Int. Microw. Symp., Seattle, Wash., June 2002, pp. 367-370,together with the commercial liquid crystal K15 from Merck KGaA. C.Weil, G. Lüssem, and R. Jakoby: Tunable Invert-Microstrip Phase ShifterDevice Using Nematic Liquid Crystals, IEEE MTT-S Int. Microw. Symp.,Seattle, Wash., June 2002, pp. 367-370, achieved phase shifter qualitiesof 12°/dB at 10 GHz with a control voltage of about 40 V therewith. Theinsertion losses of the LC, i.e. the losses caused only by thepolarisation losses in the liquid crystal, are given as approximately 1to 2 dB at 10 GHz in Weil, C.: Passiv steuerbareMikrowellenphasenschieber auf der Basis nichtlinearer Dielektrika[Passively Controllable Microwave Phase Shifters based on NonlinearDielectrics], Darmstädter Dissertationen D17, 2002. In addition, it hasbeen determined that the phase shifter losses are determined primarilyby the dielectric LC losses and the losses at the waveguide junctions.T. Kuki, H. Fujikake, H. Kamoda and T. Nomoto: Microwave Variable DelayLine Using a Membrane Impregnated with Liquid Crystal. IEEE MTT-S Int.Microwave Symp. Dig. 2002, pp. 363-366, June 2002, and T. Kuki, H.Fujikake, T. Nomoto: Microwave Variable Delay Line Using Dual-FrequencySwitching-Mode Liquid Crystal. IEEE Trans. Microwave Theory Tech., Vol.50, No. 11, pp. 2604-2609, November 2002, also address the use ofpolymerised LC films and dual-frequency switching-mode liquid crystalsin combination with planar phase shifter arrangements.

A. Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R.Jakoby: “Cavity Perturbation Method for Characterization of LiquidCrystals up to 35 GHz”, 34^(th) European Microwave Conference—Amsterdam,pp. 545-548 describe, inter alia, the properties of the known singleliquid-crystalline substance K15 (Merck KGaA, Germany) at a frequency of9 GHz.

A. Gaebler, F. Goelden, S. Müller, A. Penirschke and R. Jakoby “DirectSimulation of Material Permittivites using an Eigen-SusceptibilityFormulation of the Vector Variational Approach”, 12MTC2009—International Instrumentation and Measurement TechnologyConference, Singapore, 2009 (IEEE), pp. 463-467, describe thecorresponding properties of the known liquid-crystal mixture E7(likewise Merck KGaA, Germany).

DE 10 2004 029 429 A describes the use of liquid-crystal media inmicrowave technology, inter alia in phase shifters.

DE 10 2004 029 429 A has already investigated liquid-crystalline mediawith respect to their properties in the corresponding frequency range.In addition, it describes liquid-crystalline media which comprisecompounds of the formulae

besides compounds of the formulae

or besides compounds of the formulae

Further development in the field aims in particular at reduction of theloss in the microwave region and improvement of the material quality(II), as disclosed e.g in WO 2011/009524.

Liquid crystalline media comprising one or more of the compoundsmentioned above, as well as similar ones, are proposed by for microwaveapplications e.g. in DE 10 2010 025 572 A1 and WO 2013/034227 A1, whichdiscloses, amongst others, liquid crystalline media comprising compoundsof the following formula

Furthermore, from the state-of-the art compounds with two triple bondsare known such as for example alkynyl tolanes (WO 2015/24635 A). Atypical example is the following compound:

Structurally related are phenylalkynyl tolanes which are disclosed infor example WO 2012/048774 and WO 2012/097853, and where the centralaromatic ring is substituted with two lateral substituents inortho-position to each other, e.g.

wherein R¹ and R² denote alkyl.

However, these compositions are afflicted with serious disadvantages.Most of them result, besides other deficiencies, in disadvantageouslyhigh losses and/or inadequate phase shifts or inadequate materialquality.

For these applications, liquid-crystalline media with particular,hitherto rather unusual and uncommon properties, or combinations ofproperties, are required.

Surprisingly, it has been found that it is possible to achieveliquid-crystalline media having a suitably high Δε, a suitable nematicphase range and Δn which do not have the disadvantages of the prior-artmaterials, or at least only do so to a considerably reduced extent.

These improved liquid-crystalline media in accordance with the presentinvention comprise

a compound of formula A

wherein

-   -   R⁰¹ is defined as R¹¹ below    -   L⁰¹ is defined as R¹¹ or X¹¹ below,        and    -   additionally one or more compounds of formula II below, and    -   optionally one or more compounds of formula I.

wherein

-   -   L¹¹ denotes R¹¹ or X¹¹,    -   L¹² denotes R¹² or X¹²,    -   R¹¹ and R¹², independently of one another, denote H,        unfluorinated alkyl or unfluorinated alkoxy having 1 to 17,        preferably having 3 to 10, C atoms or unfluorinated alkenyl,        unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2        to 15, preferably 3 to 10, C atoms, preferably unfluorinated        alkyl or unfluorinated alkenyl,    -   X¹¹ and X¹², independently of one another, denote H, F, Cl, —CN,        —NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to        7 C atoms or fluorinated alkenyl, unfluorinated or fluorinated        alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2        to 7 C atoms, preferably fluorinated alkoxy, fluorinated        alkenyloxy, F or Cl, and

-   -    to

-   -    independently of one another, denote

-   -    preferably

wherein

-   -   L²¹ denotes R²¹ and, in the case where Z²¹ and/or Z²² denote        trans-CH═CH— or trans-CF═CH—, alternatively denotes X²¹,    -   L²² denotes R²² and, in the case where Z²¹ and/or Z²² denote        trans-CH═CH— or trans-CF═CF—, alternatively denotes X²²,    -   R²¹ and R²², independently of one another, denote H,        unfluorinated alkyl or unfluorinated alkoxy having 1 to 17,        preferably having 3 to 10, C atoms or unfluorinated alkenyl,        unfluorinated alkynyl, unfluorinated alkenyloxy or unfluorinated        alkoxyalkyl having 2 to 15, preferably 3 to 10 C atoms,        preferably unfluorinated alkyl, alkenyl or alkynyl,    -   X²¹ and X²², independently of one another, denote F or Cl, —CN,        —NCS, —SF₅, fluorinated alkyl or alkoxy having 1 to 7 C atoms or        fluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 7 C        atoms, or —NCS, preferably —NCS,    -   Z²¹ and Z²² denotes trans-CH═CH—, trans-CF═CF—, —C≡C— or a        single bond, with the proviso that at least one of Z²¹ and Z²²        denotes —C≡C—,

-   -    to

-   -    independently of one another, denote

-   -    and    -   n denotes 0 or 1,

In a preferred embodiment of the present invention, the liquid-crystalmedium comprises one or more compounds of the formula A selected fromthe group of the compounds of the sub-formulae A-1 and A-2

wherein R⁰¹ and R⁰² denote alkyl with 1 to 7 C atoms and X⁰¹ denotes F,Cl, —NCS, —SF₅, fluorinated alkyl, fluorinated alkenyl or fluorinatedalkoxy having 1 to 7 C atoms.

In a preferred embodiment of the present invention, the liquid-crystalmedium comprises one or more compounds of the formula I, preferablyselected from the group of the compounds of the formulae I-1 to I-3

wherein the parameters have the respective meanings indicated above forformula I and preferably

-   R¹¹ denotes unfluorinated alkyl having 1 to 7 C atoms or    unfluorinated alkenyl having 2 to 7 C atoms,-   R¹² denotes unfluorinated alkyl having 1 to 7 C atoms or    unfluorinated alkenyl having 2 to 7 C atoms or unfluorinated alkoxy    having 1 to 7 C atoms,-   X¹¹ and X¹², independently of one another, denote F, Cl, OCF₃, CF₃,    —CN, —NCS or SF₅, preferably F, Cl, OCF₃ or —CN.

The compounds of the formula I-1 are preferably selected from the groupof the compounds of the formulae I-1a to I-1d

wherein the parameters have the respective meanings indicated above forformula I-1 and wherein

-   Y¹¹ and Y¹² independently of one another, denote H or F, and    preferably-   R¹¹ denotes alkyl or alkenyl, and-   X¹² denotes F, Cl or OCF₃.

The compounds of the formula I-2 are preferably selected from the groupof the compounds of the formulae I-2a to I-2e and/or from the group ofthe compounds of the formulae I-2f and I-2g

where in each case the compounds of the formula I-2a are excluded fromthe compounds of the formulae I-2b and I-2c, the compounds of theformula I-2b are excluded from the compounds of the formulae I-2c andthe compounds of the formula I-2g are excluded from the compounds of theformulae I-2f, andwherein the parameters have the respective meanings indicated above forformula I-1 and wherein

-   Y¹¹ and Y¹² each, independently of one another, denote H or F, and    preferably-   R¹² denotes alkyl or alkenyl,-   Y¹¹ and Y¹² denotes H and the other denotes H or F, preferably    likewise denotes H.

The compounds of the formula I-3 are preferably compounds of the formulaI-3a:

wherein the parameters have the respective meanings indicated above forformula I-1 and wherein preferably

-   X¹¹ denotes F, Cl, preferably F,-   X¹² denotes F, Cl or —OCF₃, preferably —OCF₃.

In an even more preferred embodiment of the present invention, thecompounds of the formula I are selected from the group of the compoundsI-1a to I-1d, preferably selected from the group of the compounds I-1cand I-1d.

The compounds of the formula I-1a are preferably selected from the groupof the compounds I-1a-1 and I-1a-2

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), wherein-   n denotes an integer in the range from 0 to 7, preferably in the    range from 1 to 5 and particularly preferably 3 or 7.

The compounds of the formula I-1b are preferably compounds of theformula I-1b-1:

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), wherein-   n denotes an integer in the range from 0 to 15, preferably in the    range from 1 to 7 and particularly preferably 1 to 5.

The compounds of the formula I-1c are preferably selected from the groupof the compounds of the formulae I-1c-1 and I-1c-4, preferably selectedfrom the group of the compounds of the formulae I-1c-1 and I-1c-2,

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), wherein-   n denotes an integer in the range from 0 to 15, preferably in the    range from 1 to 7 and particularly preferably 1 to 5.

The compounds of the formula I-1d are preferably selected from the groupof the compounds of the formulae I-1d-1 and I-1d-2, preferably from thecompound of the formula I-1d-2,

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), wherein-   n denotes an integer in the range from 0 to 15, preferably in the    range from 1 to 7 and particularly preferably 1 to 5.

The compounds of the formula I-2a are preferably selected from the groupof the compounds of the formulae I-2a-1 and I-2a-2, preferably from thecompounds of the formula I-2a-1,

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

Preferred combinations of (R¹¹ and R¹²), in particular in formulaI-2a-1, are (C_(n)H_(2n+1) and C_(m)H_(2m+1)), (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), (CH₂═CH—(CH₂)_(Z) and C_(m)H_(2m+1)),(CH₂═CH—(CH₂)_(Z) and O—C_(m)H_(2m+1)) and (C_(n)H_(2n+1) and(CH₂)_(Z)—CH═CH₂).

Preferred compounds of the formula I-2b are the compounds of the formulaI-2b-1:

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R¹¹ and R¹²) here is, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

Preferred compounds of the formula I-2c are the compounds of the formulaI-2c-1:

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R¹¹ and R¹²) here is, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

Preferred compounds of the formula I-2d are the compounds of the formulaI-2d-1:

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R¹¹ and R¹²) here is, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

Preferred compounds of the formula I-2e are the compounds of the formulaI-2e-1:

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R¹¹ and R¹²) here is, in particular,(C_(n)H_(2n+1) and O—C_(m)H_(2m+1)).

Preferred compounds of the formula I-2f are the compounds of the formulaI-2f-1:

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R¹¹ and R¹²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

Preferred compounds of the formula I-2g are the compounds of the formulaI-2g-1:

wherein

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R¹¹ and R¹²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

The compounds of the formula II are preferably selected from the groupof the compounds of the formulae II-1 to II-6,

wherein

-   Z²¹ and Z²² denote trans-CH═CH— or trans-CF═CF—, preferably    trans-CH═CH—, and the other parameters have the meaning given above    under formula II, and preferably-   R²¹ and R²², independently of one another, denote H, unfluorinated    alkyl or unfluorinated alkoxy having 1 to 17, preferably having 3 to    10, C atoms or unfluorinated alkenyl, unfluorinated alkynyl,    unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to    15, preferably 3 to 10 C atoms, preferably unfluorinated alkyl,    alkenyl or alkynyl,-   X²² denotes F, Cl, —CN or —NCS, preferably —NCS,    and one of

to

denotes

-   -   and the others independently of each other denote

and preferably

-   R²¹ denotes C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R²² denotes C_(m)H_(2m+1) or O—C_(m)H_(2m+1), (CH₂)_(Z)—CH═CH₂ or    —C≡C—(CH₂)_(Z−1)CH₃ and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2,    and where the compounds of the formula II-3 are excluded from the    compounds of the formula II-2.

The compounds of the formula II-1 are preferably selected from the groupof the compounds of the formulae II-1a and II-1b:

wherein

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R²² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1), (CH₂)_(Z)—CH═CH₂ or    —C≡C—(CH₂)_(y)CH₃ and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   y denotes 0, 1, 2, 3 or 4, preferably 0,-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

In a particularly preferred embodiment the compounds of formula II-1aand II-1b are selected from the group of compounds of the formulaeII-1a-1 and II-1a-2

wherein R²¹ and R²² denote alkyl with 1 to 6 C atoms.

The compounds of the formula II-2 are preferably selected from the groupof the compounds of the formulae II-2a and II-2b, preferably selectedfrom the group of the compounds of the formula II-2a,

wherein

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R²² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R²¹ and R²²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)) in the case of formula II-1a and particularly preferably(C_(n)H_(2n+1) and O—C_(m)H_(2m+1)) in the case of formula II-1b.

The compounds of the formula II-3 are preferably compounds of theformula II-3a:

wherein

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R²² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R²¹ and R²²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

The compounds of the formula II-4 are preferably compounds of theformula II-4a:

wherein the parameters have the meanings indicated above for formulaII-4 and preferably

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), wherein-   n denotes an integer in the range from 0 to 7, preferably in the    range from 1 to 5, and-   X²² denotes —F, —Cl, —OCF₃, —CN or —NCS, particularly preferably    —NCS.

The compounds of the formula II-5 are preferably compounds of theformula II-5a:

wherein the parameters have the meanings indicated above for formulaII-4 and preferably

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), wherein-   n denotes an integer in the range from 0 to 7, preferably in the    range from 1 to 5, and-   X²² denotes —F, —Cl, —OCF₃, —CN or —NCS, particularly preferably    —NCS.

Further preferred compounds of the formula II are the compounds of thefollowing formulae:

wherein

-   n denotes an integer in the range from 0 to 7, preferably in the    range from 1 to 5.

The compounds of the formula II-6 are preferably selected from the groupof compounds of the formulae II-6a to

wherein R²¹ and R²² denote alkyl having 1 to 6 carbon atoms.

The media according to the present invention optionally comprise one ormore compounds of formula III

wherein

-   L³¹ denotes R³¹ or X³¹,-   L³² denotes R³² or X³²,-   R³¹ and R³², independently of one another, denote H, unfluorinated    alkyl or unfluorinated alkoxy having 1 to 17, preferably having 3 to    10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or    unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C    atoms, preferably unfluorinated alkyl or unfluorinated alkenyl,-   X³¹ and X³², independently of one another, denote H, F, Cl, —CN,    —NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C    atoms or fluorinated alkenyl, unfluorinated or fluorinated    alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2 to 7    C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or    Cl, and-   Z³¹ to Z³³, independently of one another, denote trans-CH═CH—,    trans-CF═CF—, —C≡C— or a single bond, preferably one or more of them    denotes a single bond, particularly preferably all denote a single    bond, and

-    to

-    independently of one another, denote

-    preferably

The compounds of the formula III are preferably selected from the groupof the compounds of the formulae III-1 to III-7,

wherein the compounds of the formula III-5 are excluded from thecompounds of the formula III-6, andwherein the parameters have the respective meanings indicated above forformula III and preferably

-   R³¹ denotes unfluorinated alkyl or alkoxy, each having 1 to 7 C    atoms, or unfluorinated alkenyl having 2 to 7 C atoms,-   R³² denotes unfluorinated alkyl or alkoxy, each having 1 to 7 C    atoms, or unfluorinated alkenyl having 2 to 7 C atoms, and-   X³² denotes F, Cl, or —OCF₃, preferably F, and-   Y³¹, Y³² denote, the same of different, H or F.

Particularly preferably

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The compounds of the formula III-1 are preferably selected from thegroup of the compounds of the formulae III-1a to III-1d,

wherein X³² has the meaning given above for formula III and

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), wherein-   n denotes 1 to 7, preferably 2 to 6, particularly preferably 2, 3 or    5,-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2, and-   X³² preferably denotes F.

The compounds of the formula III-2 are preferably selected from thegroup of the compounds of the formulae III-2a and III-2b, preferably ofthe formula III-2a,

wherein

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula III-3 are preferably compounds of theformula III-3a:

wherein

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula III-4 are preferably compounds of theformula III-4a:

wherein

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula III-5 are preferably selected from thegroup of the compounds of the formulae III-5a and III-5b, preferably ofthe formula III-5a,

wherein

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula III-6 are preferably selected from thegroup of the compounds of the formulae III-6a and III-6b,

wherein

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The media in accordance with the present invention optionally compriseone or more compounds of the formula IV

wherein

-   R⁴¹ and R⁴², independently of one another, denote H, unfluorinated    alkyl or alkoxy having 1 to 15, preferably 3 to 10, C atoms or    unfluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 15,    preferably 3 to 10, C atoms, preferably unfluorinated alkyl or    alkenyl,-   one of-   Z⁴¹ and Z⁴² denotes trans-CH═CH—, trans-CF═CF— or —C≡C— and the    other denotes, independently thereof, trans-CH═CH—, trans-CF═CF— or    a single bond, preferably one of them denotes —C≡C— or trans-CH═CH—    and the other denotes a single bond, and

-    denotes

-    independently of one another, denote

The compounds of the formulae IV are preferably selected from the groupof the compounds of the formulae IV-1 to IV-3,

wherein

-   one of-   Y⁴¹ and Y⁴² denotes H and the other denotes H or F, and-   R⁴¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁴² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁴¹ and R⁴²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formulae IV-1 are preferably selected from thegroup of the compounds of the formulae IV-1a to IV-1c,

wherein

-   R⁴¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁴² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁴¹ and R⁴²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The media in accordance with the present invention optionally compriseone or more compounds of the formula V

wherein

-   L⁵¹ denotes R⁵¹ or X⁵¹,-   L⁵² denotes R⁵² or X⁵²,-   R⁵¹ and R⁵², independently of one another, denote H, unfluorinated    alkyl or alkoxy having 1 to 15, preferably 3 to 10 C atoms or    unfluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 15,    preferably 3 to 10, C atoms, preferably unfluorinated alkyl or    alkenyl,-   X⁵¹ and X⁵², independently of one another, denote H, F, Cl, —CN,    —NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C    atoms or fluorinated alkenyl, unfluorinated or fluorinated    alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2 to 7    C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or    Cl, and-   Z⁵¹ to Z⁵³, independently of one another, denote trans-CH═CH—,    trans-CF═CF—, —C≡C— or a single bond, preferably one or more of them    denotes a single bond, and particularly preferably all denote a    single bond,

-    denotes

-    to

-    independently of one another, denote

The compounds of the formula V are preferably selected from the group ofthe compounds of the formulae V-1 to V-3,

wherein the parameters have the respective meanings indicated aboveunder formula V and preferablyone of

to

denotes

andwherein

-   R⁵¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z),-   R⁵² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂,-   X⁵² has the meaning indicated above,-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁵¹ and R⁵²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

The compounds of the formula V-1 are preferably selected from the groupof the compounds of the formulae V-1a to V-1e, more preferably thesecompounds of the formula V-1 predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

wherein the parameters have the meaning given above and preferably

-   R⁵¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), and-   n denotes an integer in the range from 0 to 15, preferably in the    range from 1 to 7 and particularly preferably 1 to 5, and-   X⁵² preferably denotes F or Cl.

The compounds of the formula V-2 are preferably selected from the groupof the compounds of the formulae V-2a and V-2b,

wherein

-   R⁵¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁵² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R⁵¹ and R⁵²) here is, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

The compounds of the formula V-3 are preferably compounds of theformulae V-3a and V-3b:

wherein

-   R⁵¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n-F1) or CH₂═CH—(CH₂)_(Z), and-   R⁵² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and wherein-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁵¹ and R⁵²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

The media in accordance with the present invention optionally compriseone or more compounds of the formula VI

wherein

-   R⁶¹, independently of each other, denote alkyl, alkoxy, fluorinated    alkyl or fluorinated alkoxy with 1 to 7 C-atoms, alkenyl,    alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C-atoms,    and R² and R³ preferably are alkyl or alkenyl,

-    to

-    are independently of each other

-    preferably

-   L⁶¹, L⁶² denote independently of each other, H or F, preferably L⁶¹    and/or L⁶² is F,-   X⁶¹ denotes halogen, halogenated alkyl or alkoxy with 1 to 3 C-atoms    or halogenated alkenyl or alkenyloxy with 2 or 3 C-atoms, preferably    F, Cl, —OCF₃ or —CF₃, most preferably F, Cl or —OCF₃,-   l, m denote independently of each other, 0 or 1.

The compounds of formula VI are preferably selected from formula VI-1

wherein the parameters have the respective meanings given under formulaVI and L⁶³ and L⁶⁴ denote H or F, preferably F.

In a preferred embodiment of the present invention the compounds offormula VI are selected from compounds of formula VI-1 wherein L⁶¹, L⁶²,L⁶³ and L⁶⁴ all are F.

Preferably the compounds of formula VI-1 are selected from the group ofcompounds of formulae VI-1a to VI-1d, particularly preferably fromcompounds of formula VI-1d,

wherein the parameters have the respective meanings given above.

The liquid crystal medium according to the present invention mayoptionally additionally comprise one or more biphenyl compounds selectedfrom the group consisting of the following formulae:

-   wherein-   alkyl and alkyl* each, independently of one another, denote a    straight-chain alkyl radical having 1-6 C atoms, and-   alkenyl and-   alkenyl* each, independently of one another, denote a straight-chain    alkenyl radical having 2-6 C atoms.-   Alkenyl and alkenyl* preferably denote CH₂═CH—, CH₂═CHCH₂CH₂—,    CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or    CH₃—CH═CH—(CH₂)₂—.

The compounds of the formula VII-2 are particularly preferred.

The compounds of the formulae VII-1 to VII-3 are preferably selectedfrom the group consisting of the following sub-formulae:

in which alkyl* denotes an alkyl radical having 1-6 C atoms. The mediumaccording to the invention particularly preferably comprises one or morecompounds of the formulae VII-1a and/or VII-2c.

The liquid crystal medium according to the present invention mayoptionally additionally comprise one or dielectrically neutral compoundsselected from the group consisting of the following formulae:

-   -   in which the individual radicals have the following meanings:

-   -    denotes

-   -    denotes

-   -   R³ and R⁴ each, independently of one another, denote alkyl        having 1 to 12 C atoms, in which, in addition, one or two        non-adjacent CH₂ groups may be replaced    -    by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that O        atoms are not linked directly to one another,    -   Z^(y) denotes —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—,        —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,        preferably a single bond.

The compounds of the formula VIII- are preferably selected from thegroup consisting of the following sub-formulae:

wherein alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferablydenotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Especially preferred are compounds of formula VIII-1 and VIII-3.

Particularly preferred compounds of formula VIII- are selected from thefollowing sub-formulae:

wherein the propyl, butyl and pentyl groups are straight-chain groups.

Most preferred are compounds of formula VIII-1a and VIII-3a.

Another subject of the present invention are compounds of formula A-2

wherein

-   -   R⁰¹ has the meaning indicated in claim 1 and    -   X⁰¹ denotes F, Cl, —NCS, —SF₅, fluorinated alkyl, fluorinated        alkenyl or fluorinated alkoxy having 1 to 7 C atoms.

Preferably, the compounds of formula A-2 are selected from the compoundsof the following sub-formulae A-2a to A-2f

The compounds of the general formula A can be prepared by methods knownper se, as described in the literature (for example in the standardworks, such as Houben-Weyl, Methoden der organischen Chemie [Methods ofOrganic Chemistry], Georg-Thieme-Verlag, Stuttgart), under reactionconditions which are known and suitable for the said reactions. Use canbe made here of variants known per se which are not mentioned here ingreater detail.

If desired, the starting materials can also be formed in situ by notisolating them from the reaction mixture, but instead immediatelyconverting them further into the compounds of the general formula I.

The syntheses of various compounds of the general formula I according tothe invention will be illustrated in the examples. The startingsubstances can be obtained by generally accessible literature proceduresor are commercially available. The reaction types described are to beregarded as known from the literature.

Particularly preferred synthetic routes to the compounds of theinvention are described below (schemes 1 and 2).

Starting from 4-bromo-2,5-difluoro-1-iodobenzene (2) compounds A can beobtained in two subsequent Sonogashira coupling steps using substitutedphenyl acetylenes 1. Alternatively, for compounds with equalsubstituents R⁰¹ and L⁰¹ the coupling can also be performed in only onestep.

Depending on the nature of the substituents it can be advantageous tostart from more readily available 1,4-dibromo-2,5-difluorobenzene (5)and separate the mixture of compounds 6 and A′ if necessary (scheme 2).

In a preferred embodiment of the present invention, the medium comprisesone or more compounds of the formulae A and II.

In another preferred embodiment of the present invention, the mediumcomprises one or more compounds of the formulae A, land II.

In a preferred embodiment of the present invention, the medium comprisesone or more dielectrically positive compounds of the formula I-1 havinga dielectric anisotropy of greater than 3.

In a first preferred embodiment the compounds of the formula II arepreferably selected from compounds of the formula II-2a and II-1a.

In a second preferred embodiment the compounds of the formula II arepreferably selected from compounds of the formula II-2a and II-1a.

In a third preferred embodiment the compounds of the formula Harepreferably selected from compounds of the formulae II-6, preferablyII-6d, or II-6d and II-6a.

In a fourth preferred embodiment the medium additionally comprises oneor more compounds of the formula II-1b-1.

According to the present invention the compounds of the formula A arepreferably used in a total concentration of 1 to 30%, preferably 5 to20% and particularly preferably 10 to 15%.

In accordance with the present invention, the individual compounds ofthe formula I are preferably used in a total concentration of 0 to 30%,more preferably 5% to 25%, even more preferably 10% to 25% and verypreferably 15% to 25% of the mixture as a whole.

The compounds of the formula Hare preferably used in a totalconcentration of 30% to 99%, more preferably 35% to 95%, even morepreferably 40% to 90% and very preferably 40% to 85% of the mixture as awhole.

The compounds of the formula II-2a are preferably used in a totalconcentration of 20% to 70%, more preferably 30% to 65%, even morepreferably 40% to 60% and very preferably 45% to 55% of the mixture as awhole.

The compounds of the formula II-1a are preferably used in a totalconcentration of 5% to 50%, more preferably 15% to 40%, even morepreferably 20% to 35% and very preferably 25% to 30% of the mixture as awhole.

The compounds of the formula II-1b-1 are preferably used in combinationwith compounds 11-2a total concentration of 1% to 30%, more preferably5% to 30%, even more preferably 10% to 20% and very preferably 14% to17% of the mixture as a whole. The compounds of the formula II-1b-1 arepreferably used in combination with compounds 11-6 total concentrationof 10% to 60%, more preferably 15% to 50%, even more preferably 20% to40% and very preferably 30% to 35% of the mixture as a whole.

The compounds of the formula II-6 are preferably used in a totalconcentration of 20% to 70%, more preferably 30% to 65%, even morepreferably 40% to 60% and very preferably 45% to 55% of the mixture as awhole.

The liquid-crystal media preferably comprise, preferably predominantlyconsist of and very preferably completely consist of in total 50% to100%, more preferably 60% to 100% and very preferably 70% to 100% of thecompounds of the formulae A, I, and II, or of the compounds A and II.

The liquid-crystalline media in accordance with the present applicationpreferably comprise in total 0 to 40%, preferably 0 to 30% andparticularly preferably 5 to 25%, of compounds of the formula IV.

The liquid-crystalline media in accordance with the present applicationpreferably comprise in total 5 to 30%, preferably 10 to 25% andparticularly preferably 15 to 20%, of compounds of the formula V.

The proportion of compounds of formula VI in the mixture is preferablyin the range from 0% to 10%, more preferably from 2% to 8% andparticularly preferably from 3% to 6%.

The proportion of the biphenyls of the formulae VII-1 to VII-3 in themixture is preferably in the range from 0% to 15%, more preferably from1% to 10% and particularly preferably from 3% to 8%.

The proportion of the compounds of the formulae VIII-1 to VIII-10 in themixture is preferably in the range from 0% to 20%, more preferably from5% to 18% and particularly preferably from 10% to 16%.

Furthermore it is preferred that the media according to the presentinvention comprise further mesogenic compounds known to the skilledperson from the state of the art in order to adapt the mixtureproperties according to the particular application. Preferred compoundsare shown in table D but other mesogenic compounds which are notexplicitly mentioned above can optionally and advantageously also beused in the media in accordance with the present invention. Suchcompounds are known to the person skilled in the art.

The definitions of the abbreviations (acronyms) are likewise indicatedbelow in Table D or are evident from Tables A to C.

The liquid-crystal media in accordance with the present inventionpreferably have a clearing point of 90° C. or more, more preferably 120°C. or more, particularly preferably 150° C. or more.

The nematic phase of the media in accordance with the inventionpreferably extends at least from −10° C. or less to 90° C. or more, morepreferably at least from −20° C. or less to 120° C. or more, mostpreferably at least from −30° C. or less to 150° C. or more.

The expression “to have a nematic phase” here means on the one hand thatno smectic phase and no crystallisation are observed at low temperaturesat the corresponding temperature and on the other hand that no clearingoccurs on heating from the nematic phase. The investigation at lowtemperatures is carried out in a flow viscometer at the correspondingtemperature and checked by storage in test cells having a layerthickness of 5 μm for at least 100 hours. At high temperatures, theclearing point is measured in capillaries by conventional methods.

The Δε of the liquid-crystal medium in accordance with the invention, at1 kHz and 20° C., is preferably 1 or more, more preferably 2 or more andvery preferably 3 or more.

In some embodiments, however, liquid crystals having a negative value ofthe dielectric anisotropy can also advantageously be used.

The Δn of the liquid-crystal media in accordance with the presentinvention, at 589 nm (Na_(D)) and 20° C., is preferably in the rangefrom 0.200 or more to 0.90 or less, more preferably in the range from0.250 or more to 0.90 or less, even more preferably in the range from0.300 or more to 0.85 or less and very particularly preferably in therange from 0.350 or more to 0.800 or less.

Furthermore, the liquid-crystal media according to the invention arecharacterised by high anisotropy values in the microwave range. Thebirefringence at about 8.3 GHz is, for example, preferably 0.14 or more,particularly preferably 0.15 or more, particularly preferably 0.20 ormore, particularly preferably 0.25 or more and very particularlypreferably 0.30 or more. In addition, the birefringence is preferably0.80 or less.

The Figure of Merit (FoM) η(μ-waves)/tan(δ) of the preferredliquid-crystal materials is 5 or more, preferably 10 or more, andparticularly preferably 20 or more.

In the present application, the expression dielectrically positivedescribes compounds or components where Δε>3.0, dielectrically neutraldescribes those where −1.5≤Δε≤3.0 and dielectrically negative describesthose where Δε<−1.5. Δε is determined at a frequency of 1 kHz and at 20°C. The dielectric anisotropy of the respective compound is determinedfrom the results of a solution of 10% of the respective individualcompound in a nematic host mixture. If the solubility of the respectivecompound in the host mixture is less than 10%, the concentration isreduced to 5%. The capacitances of the test mixtures are determined bothin a cell having homeotropic alignment and in a cell having homogeneousalignment. The cell thickness of both types of cells is approximately 20μm. The voltage applied is a rectangular wave having a frequency of 1kHz and an effective value of typically 0.5 V to 1.0 V, but it is alwaysselected to be below the capacitive threshold of the respective testmixture.

Δε is defined as (ε_(∥)−ε_(⊥)), while ε_(ave.) is (ε_(∥)+2ε_(⊥))/3.

The host mixture used for dielectrically positive compounds is mixtureZLI-4792 and that used for dielectrically neutral and dielectricallynegative compounds is mixture ZLI-3086, both from Merck KGaA, Germany.The absolute values of the dielectric constants of the compounds aredetermined from the change in the respective values of the host mixtureon addition of the compounds of interest. The values are extrapolated toa concentration of the compounds of interest of 100%.

Components having a nematic phase at the measurement temperature of 20°C. are measured as such, all others are treated like compounds.

The expression threshold voltage in the present application refers tothe optical threshold and is quoted for 10% relative contrast (V₁₀), andthe expression saturation voltage refers to the optical saturation andis quoted for 90% relative contrast (V₉₀), in both cases unlessexpressly stated otherwise. The capacitive threshold voltage (V₀), alsocalled the Freedericks threshold (V_(Fr)), is only used if expresslymentioned.

The parameter ranges indicated in this application all include the limitvalues, unless expressly stated otherwise.

The different upper and lower limit values indicated for various rangesof properties in combination with one another give rise to additionalpreferred ranges.

Throughout this application, the following conditions and definitionsapply, unless expressly stated otherwise. All concentrations are quotedin percent by weight and relate to the respective mixture as a whole,all temperatures are quoted in degrees Celsius and all temperaturedifferences are quoted in differential degrees. All physical propertiesare determined in accordance with “Merck Liquid Crystals, PhysicalProperties of Liquid Crystals”, Status November 1997, Merck KGaA,Germany, and are quoted for a temperature of 20° C., unless expresslystated otherwise. The optical anisotropy (Δn) is determined at awavelength of 589.3 nm. The dielectric anisotropy (Δε) is determined ata frequency of 1 kHz. The threshold voltages, as well as all otherelectro-optical properties, are determined using test cells produced atMerck KGaA, Germany. The test cells for the determination of Δε have acell thickness of approximately 20 μm. The electrode is a circular ITOelectrode having an area of 1.13 cm² and a guard ring. The orientationlayers are SE-1211 from Nissan Chemicals, Japan, for homeotropicorientation (ε_(∥)) and polyimide AL-1054 from Japan Synthetic Rubber,Japan, for homogeneous orientation (ε_(⊥)). The capacitances aredetermined using a Solatron 1260 frequency response analyser using asine wave with a voltage of 0.3 V_(rms). The light used in theelectro-optical measurements is white light. A set-up using acommercially available DMS instrument from Autronic-Melchers, Germany,is used here. The characteristic voltages have been determined underperpendicular observation. The threshold (V₁₀), mid-grey (V₅₀) andsaturation (V₉₀) voltages have been determined for 10%, 50% and 90%relative contrast, respectively.

The liquid-crystalline media are investigated with respect to theirproperties in the microwave frequency range as described in A.Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R.Jakoby: “Cavity Perturbation Method for Characterization of LiquidCrystals up to 35 GHz”, 34^(th) European Microwave Conference—Amsterdam,pp. 545-548.

Compare in this respect also A. Gaebler, F. Gölden, S. Müller, A.Penirschke and R. Jakoby “Direct Simulation of Material Permittivites .. . ”, 12MTC 2009—International Instrumentation and MeasurementTechnology Conference, Singapore, 2009 (IEEE), pp. 463-467, and

DE 10 2004 029 429 A, in which a measurement method is likewisedescribed in detail.

The dielectric anisotropy in the microwave region is defined asΔε_(r)=(ε_(r,∥)−ε_(r,⊥)).

The tuneability (τ) is defined asτ≡(Δε_(r)/ε_(r,∥)).

The material quality (η) is defined asη≡(τ/tan δ_(ε) _(r,max) ), wherethe maximum dielectric loss istan δ_(ε) _(r,max) =max.{tan δ_(ε) _(r,⊥) ;tan δ_(ε) _(r,∥) }.

The liquid crystal is introduced into a polytetrafluoroethylene (PTFE)capillary. The capillary has an internal radius of 180 μm and anexternal radius of 350 μm. The effective length is 2.0 cm. The filledcapillary is introduced into the centre of the cavity with a resonancefrequency of 30 GHz. This cavity has a length of 6.6 mm, a width of 7.1mm and a height of 3.6 mm. The input signal (source) is then applied,and the result of the output signal is recorded using a commercialvector network analyser.

The change in the resonance frequency and the Q factor between themeasurement with the capillary filled with the liquid crystal and themeasurement without the capillary filled with the liquid crystal is usedto determine the dielectric constant and the loss angle at thecorresponding target frequency by means of equations 10 and 11 in A.Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R.Jakoby: “Cavity Perturbation Method for Characterization of LiquidCrystals up to 35 GHz”, 34^(th) European Microwave Conference—Amsterdam,pp. 545-548, as described therein.

The values for the components of the properties perpendicular andparallel to the director of the liquid crystal are obtained by alignmentof the liquid crystal in a magnetic field. To this end, the magneticfield of a permanent magnet is used. The strength of the magnetic fieldis 0.35 tesla. The alignment of the magnets is set correspondingly andthen rotated correspondingly through 90°.

Preferred components are phase shifters, varactors, wireless and radiowave antenna arrays, matching circuit adaptive filters and others.

In the present application, the term compounds is taken to mean both onecompound and a plurality of compounds, unless expressly statedotherwise.

The liquid crystals employed are either individual substances ormixtures. They preferably have a nematic phase.

The term “alkyl” preferably encompasses straight-chain and branchedalkyl groups having 1 to 15 carbon atoms, in particular thestraight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl andheptyl. Groups having 2 to 10 carbon atoms are generally preferred.

The term “alkenyl” preferably encompasses straight-chain and branchedalkenyl groups having 2 to 15 carbon atoms, in particular thestraight-chain groups. Particularly preferred alkenyl groups are C₂- toC₇-1E-alkenyl, C₄- to C₇-3E-alkenyl, C₅- to C₇-4-alkenyl, C₆- toC₇-5-alkenyl and C₇-6-alkenyl, in particular C₂- to C₇-1E-alkenyl, C₄-to C₇-3E-alkenyl and C₅- to C₇-4-alkenyl. Examples of further preferredalkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl,1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl,3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl,6-heptenyl and the like. Groups having up to 5 carbon atoms aregenerally preferred.

The term “fluoroalkyl” preferably encompasses straight-chain groupshaving a terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl,3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and7-fluoroheptyl. However, other positions of the fluorine are notexcluded.

The term “oxaalkyl” or “alkoxyalkyl” preferably encompassesstraight-chain radicals of the formula C_(n)H_(2n+1)—O—(CH₂)_(m),wherein n and m each, independently of one another, denote 1 to 10.Preferably, n is 1 and m is 1 to 6.

Compounds containing a vinyl end group and compounds containing a methylend group have low rotational viscosity.

In the present application, both high-frequency technology andhyperfrequency technology denote applications having frequencies in therange from 1 MHz to 1 THz, preferably from 1 GHz to 500 GHz, morepreferably 2 GHz to 300 GHz, particularly preferably from about 5 to 150GHz.

The liquid-crystal media in accordance with the present invention maycomprise further additives and chiral dopants in the usualconcentrations. The total concentration of these further constituents isin the range from 0% to 10%, preferably 0.1% to 6%, based on the mixtureas a whole. The concentrations of the individual compounds used are eachpreferably in the range from 0.1% to 3%. The concentration of these andsimilar additives is not taken into consideration when quoting thevalues and concentration ranges of the liquid-crystal components andliquid-crystal compounds of the liquid-crystal media in thisapplication.

The liquid-crystal media according to the invention consist of aplurality of compounds, preferably 3 to 30, more preferably 4 to 20 andvery preferably 4 to 16 compounds. These compounds are mixed in aconventional manner. In general, the desired amount of the compound usedin the smaller amount is dissolved in the compound used in the largeramount. If the temperature is above the clearing point of the compoundused in the higher concentration, it is particularly easy to observecompletion of the dissolution process. It is, however, also possible toprepare the media in other conventional ways, for example usingso-called pre-mixes, which can be, for example, homologous or eutecticmixtures of compounds, or using so-called “multibottle” systems, theconstituents of which are themselves ready-to-use mixtures.

All temperatures, such as, for example, the melting point T(C,N) orT(C,S), the transition from the smectic (S) to the nematic (N) phaseT(S,N) and the clearing point T(N,I) of the liquid crystals, are quotedin degrees Celsius. All temperature differences are quoted indifferential degrees.

In the present invention and especially in the following examples, thestructures of the mesogenic compounds are indicated by means ofabbreviations, also referred to as acronyms. In these acronyms, thechemical formulae are abbreviated as follows using Tables A to C below.All groups C_(n)H_(2n+1), C_(m) H_(2m+1) and C_(l)H_(2l+1) orC_(n)H_(2n−1), C_(m)H_(2m−1) and C_(l)H_(2l−1) denote straight-chainalkyl or alkenyl, preferably 1-E-alkenyl, respectively, in each casehaving n, m or I C atoms. Table A lists the codes used for the ringelements of the core structures of the compounds, while Table B showsthe linking groups. Table C gives the meanings of the codes for theleft-hand or right-hand end groups. Table D shows illustrativestructures of compounds with their respective abbreviations.

TABLE A Ring elements C

D

DI

A

AI

P

P(1)

P(1)I

P(c3)

P(c3)I

G

GI

U

UI

Y

X

M

MI

N

NI

Np

iNp

N3f

N3fI

tH

tHI

tH2f

tH2fI

dH

K

KI

L

LI

F

FI

TABLE B Linking groups E —CH₂CH₂— Z —CO—O— V —CH═CH— ZI —O—CO— X —CF═CH—O —CH₂—O— XI —CH═CF— OI —O—CH₂— B —CF═CF— Q —CF₂—O— T —C≡C— QI —O—CF₂— W—CF₂CF₂—

TABLE C End groups Left-hand side Right-hand side Use alone -n-C_(n)H_(2n+1)— -n —C_(n)H_(2n+1) -nO- C_(n)H_(2n+1)—O— -nO—O—C_(n)H_(2n+1) -V- CH₂═CH— -V —CH═CH₂ -nV- C_(n)H_(2n+1)—CH═CH— -nV—C_(n)H_(2n)—CH═CH₂ -Vn- CH₂═CH—C_(n)H_(2n+1)— -Vn —CH═CH—C_(n)H_(2n+1)-nVm- C_(n)H_(2n+1)—CH═CH—C_(m)H_(2m)— -nVm—C_(n)H_(2n)—CH═CH—C_(m)H_(2m+1) -N- N≡C— -N —C≡N -S- S═C═N— -S —N═C═S-F- F— -F —F -CL- Cl— -CL —Cl -M- CFH₂— -M —CFH₂ -D- CF₂H— -D —CF₂H -T-CF₃— -T —CF₃ -MO- CFH₂O— -OM —OCFH₂ -DO- CF₂HO— -OD —OCF₂H -TO- CF₃O—-OT —OCF₃ -OXF- CF₂═CH—O— -OXF —O—CH═CF₂ -A- H—C≡C— -A —C≡C—H -nA-C_(n)H_(2n+1)—C≡C— -An —C≡C—C_(n)H_(2n+1) -NA- N≡C—C≡C— -AN —C≡C—C≡N Usetogether with others - . . . A . . . - —C≡C— - . . . A . . . —C≡C— - . .. V . . . - CH═CH— - . . . V . . . —CH═CH— - . . . Z . . . - —CO—O— - .. . Z . . . —CO—O— - . . . ZI . . . - —O—CO— - . . . ZI . . . —O—CO— - .. . K . . . - —CO— - . . . K . . . —CO— - . . . W . . . - —CF═CF— - . .. W . . . —CF═CF—wherein n and m each denote integers, and the three dots “ . . . ” areplaceholders for other abbreviations from this table.

The following table shows illustrative structures together with theirrespective abbreviations. These are shown in order to illustrate themeaning of the rules for the abbreviations. They furthermore representcompounds which are preferably used.

TABLE D Illustrative structures Illustrative structures of compoundshaving two 6-membered rings which are particularly preferably employed:

PTP-n-m

PTP(1)I-n-Am Illustrative structures of compounds having a naphthalinering which are particularly preferably employed:

PTiNpTP-n-m Illustrative structures of compounds having three 6-memberedrings which are particularly preferably employed:

PTXTP-n-m

PTXTP-n-F

PTP(c3)TP-n-m

PTPTP-n-m

PGP-n-m

PGP-F-OT

PGP-n-mV

PGP-n-mVI

PYP-n-m

GGP-n-F

GGP-n-CL

GGP-n-m

PGIGI-n-F

PGIGI-n-CL

PGU-n-F

PGU-n-CL

PGU-n-OT

PPTUI-n-m

PPTY-n-m Illustrative structures of compounds having four 6-memberedrings which are particularly preferably employed:

PGGP-n-m

PGIGP-n-m

PGIGP-n-Om

PGIGP-nO-m

PYGP-n-m

GGPP-n-m

PPGU-n-F

PPGU-Vn-F Illustrative structures of dielectrically neutral compoundswhich are preferably employed:

CPTP-n-m

CPPC-n-m

CGPC-n-m

CCZPC-n-m

CPGP-n-m

CPGP-n-mV

CPGP-n-mVI Illustrative structures of further compounds which arepreferably employed:

CC-n-m

CC-n-Om

CC-n-V

CC-n-Vm

CC-n-mV

CC-n-mVI

CC-V-V

CC-V-mV

CC-V-Vm

CC-Vn-mV

CC-nV-mV

CC-nV-Vm

CP-n-m

CP-nO-m

CP-n-Om

CP-V-m

CP-Vn-m

CP-nV-m

CP-V-V

CP-V-mV

CP-V-Vm

CP-Vn-mV

CP-nV-mV

CP-nV-Vm

PP-n-m

PP-nO-m

PP-n-Om

PP-n-V

PP-n-Vm

PP-n-mV

PP-n-mVI

CCP-n-m

CCP-nO-m

CCP-n-Om

CCP-n-V

CCP-n-Vm

CCP-n-mV

CCP-n-mVI

CCP-V-m

CCP-nV-m

CCP-Vn-m

CCP-nVm-I

CCP-n-m

CPG-n-m

CGP-n-m

CPP-nO-m

CPP-n-Om

CPP-V-m

CPP-nV-m

CPP-Vn-m

CPP-nVm-I

CGU-n-F

CCPU-n-F

CCGU-n-F

CPGU-n-F

CPGU-n-OT

PUQU-n-F

PGUQU-n-F

DPGU-n-F

DPGU-n-OT

APGP-n-m

The following table, Table E, shows illustrative compounds which can beused as stabiliser in the mesogenic media in accordance with the presentinvention. The total concentration of these and similar compounds in themedia is preferably 5% or less.

TABLE E

In a preferred embodiment of the present invention, the mesogenic mediacomprise one or more compounds selected from the group of the compoundsfrom Table E.

The following table, Table F, shows illustrative compounds which canpreferably be used as chiral dopants in the mesogenic media inaccordance with the present invention.

TABLE F

C 15

CB 15

CM 21

CM 44

CM 45

CM 47

CC

CN

R/S-811

R/S-1011

R/S-2011

R/S-3011

R/S-4011

R/S-5011

In a preferred embodiment of the present invention, the mesogenic mediacomprise one or more compounds selected from the group of the compoundsfrom Table F.

The mesogenic media in accordance with the present applicationpreferably comprise two or more, preferably four or more, compoundsselected from the group consisting of the compounds from the abovetables.

The liquid-crystal media in accordance with the present inventionpreferably comprise

-   -   seven or more, preferably eight or more, compounds, preferably        compounds having three or more, preferably four or more,        different formulae, selected from the group of the compounds        from Table D.

Unless indicated otherwise, all saturated carbocycles preferably havetrans-configuration where it is possible.

The compounds from table D are known to the expert and can besynthesised according to procedures described elsewhere.

All percentages given above and below are percent by mass based on thetotal mixture.

EXAMPLES

The examples below illustrate the present invention without limiting itin any way.

Synthesis

4-Alkylphenylacetylenes and 4-fluorophenylacetylene are known to theliterature and were synthesised as described therein.

1.1-(4-Butyl-phenylethynyl)-2,5-difluoro-4-(4-hexyl-phenylethynyl)benzene1.1 1-Bromo-4-(4-ethyl-phenylethynyl)-2,5-difluoro-benzene and1,4-Bis-(4-hexyl-phenylethynyl)-2,5-difluoro-benzene

To a mixture of 1,4-dibromo-2,5-difluorobenzene (101 g, 0.37 mol),bis(triphenylphosphine)palladium(II)chloride (15.0 g, 0.02 mol) andcopper(I)iodid (2.0 g, 0.01 mol) in diisopropylamine (500 ml) a solutionof 4-hexylphenylacetylene (CAS 79887-11-9, 93.2 g, 0.50 mol) indiisopropylamine (1.00 l) is added dropwise at 70° C. The reaction isstirred at room temp. overnight, filtered and the solvent is evaporatedi. vac. The product mixture is separated by column chromatography withpetrol ether on silica to give1-bromo-4-(4-ethyl-phenylethynyl)-2,5-difluoro-benzene and1,4-bis-(4-hexyl-phenylethynyl)-2,5-difluoro-benzene. The latter isrecrystallised from petrol ether to give colourless crystals, m.p. 94°C.

1.21-(4-Butyl-phenylethynyl)-2,5-difluoro-4-(4-hexyl-phenylethynyl)benzene

To a mixture of 1-bromo-4-(4-ethyl-phenylethynyl)-2,5-difluoro-benzene(19.5 g, 45.5 mmol), bis(triphenylphosphin)palladium(II)chlorid (1.5 g,2.0 mmol) and copper(I)iodid (0.2 g, 1.0 mmol) in diisopropylamine (50ml) a solution of 4-butylphenylacetylene (9.0 g, 56.9 mmol) indiisopropylamine (100 ml) is added dropwise at 70° C. The reaction isstirred at room temp. overnight, filtered and the solvent is evaporatedi. vac. The product is purified by column chromatography with petrolether on silica and recrystallised from petrol ether to give1-(4-butyl-phenylethynyl)-2,5-difluoro-4-(4-hexyl-phenylethynyl)-benzeneas colourless crystals, m.p. 73° C.

2.1-(4-Butyl-phenylethynyl)-2,5-difluoro-4-(4-fluoro-phenylethynyl)benzene2.1 1-Bromo-2,5-difluoro-4-(4-fluoro-phenylethynyl)-benzene

To a mixture of 1,4-dibromo-2,5-difluorobenzene (171.3 g, 0.63 mol),bis(triphenylphosphin)palladium(II)chloride (11.7 g, 16.6 mmol) andcopper(I)iodide (1.6 g, 8.3 mmol) in diisopropylamine (500 ml) asolution of 4-fluorophenylacetylene (50.0 g, 0.42 mol) indiisopropylamine (1000 ml) is added dropwise at 70° C. The reaction isstirred at room temp. overnight, filtered and the solvent is evaporatedi. vac. The product is purified by column chromatography with petrolether on silica and recrystallised from petrol ether to give1-bromo-2,5-difluoro-4-(4-fluoro-phenylethynyl)benzene as colourlesscrystals.

2.21-(4-Butyl-phenylethynyl)-2,5-difluoro-4-(4-fluoro-phenylethynyl)benzene

To a mixture of 1-bromo-2,5-difluoro-4-(4-fluoro-phenylethynyl)-benzene(16.0 g, 45.0 mmol), bis(triphenylphosphin)palladium(II)chloride (1.5 g,2.0 mmol) and copper(I)iodide (0.2 g, 1.0 mmol) in diisopropylamine (80ml) a solution of 4-butylphenylacetylen (8.5 g, 54.0 mmol) indiisopropylamine (100 ml) is added dropwise at 70° C. The reaction isstirred at room temp. overnight, filtered and the solvent is evaporatedi. vac. The product is purified by column chromatography with petrolether on silica and recrystallised from petrol ether to give1-(4-Ethyl-phenylethynyl)-2,5-difluoro-4-(4-fluoro-phenylethynyl)-benzeneas colourless crystals, m.p. 99° C.

The following table 1 shows the phase sequences of the examples 1 and 2and of further compounds obtained in analogy to the above describedsyntheses.

TABLE 1 Example R⁰¹ L⁰¹ Phase (T/° C.) 1 C₄H₉ C₆H₁₃ K 73 N 157 I 2 C₄H₉F K 99 N 162 I 3 C₃H₇ C₆H₁₃ K 67 N 169 I 4 C₃H₇ F K 105 N 179 I 5 C₅H₁₁F K 109 N 163 I 6 C₆H₁₃ F K 108 N 150 I 7 C₆H₁₃ C₆H₁₃ K 94 N 149 I 8C₃H₇ C₃H₇ K 153 N 199 I 9 C₄H₉ C₄H₉ K 100 N 167 I 10 C₅H₁₁ C₅H₁₁ K 87 N172 I

MIXTURE EXAMPLES

The examples are compared to reference mixtures from the state of theart that do not contain compounds of formula A of the present invention.

Examples 1.1 to 1.4

The following reference mixture (RM-1) and Mixture examples M-1 to M-4are prepared and investigated.

Mixture RM-1 Composition Compound Concentration/ No. Abbreviation % byweight 1 CC-3-V 16.0 2 PP-1-2V1 6.0 3 PPTUI-3-2 20.0 4 PPTUI-3-4 38.0 5GGP-5-CL 18.0 6 PGUQU-5-F 2.0 Σ 100.0 Physical properties T (N, I) =123.0° C. Δn (20° C., 589 nm) = 0.2838 Δε (20°, 1 kHz) = 3.2 γ₁ (20° C.)= 253 mPa · s k₁₁ (20° C.) = 17.5 pN k₃₃ (20° C.) = 23.3 pN

Mixture M-1 Composition Compound Concentration/ No. Abbreviation % byweight 1 CC-3-V 16.0 2 PP-1-2V1 6.0 3 PPTUI-3-2 15.0 4 PPTUI-3-4 28.0 5GGP-5-CL 18.0 6 PGUQU-5-F 2.0 7 PTXTP-4-6 5.0 8 PTXTP-3-F 5.0 9PTXTP-4-F 5.0 Σ 100.0 Physical properties T (N, I) = 122.0° C. Δn (20°C., 589 nm) = N/A Δε (20°, 1 kHz) = 3.6 γ1 (20° C.) = 269 mPa · s k₁₁(20° C.) = 16.8 pN k₃₃ (20° C.) = 25.4 pN

Mixture M-2 Composition Compound Concentration/ No. Abbreviation % byweight 1 CC-3-V 16.0 2 PP-1-2V1 6.0 3 PPTUI-3-2 20.0 4 PPTUI-3-4 30.0 5GGP-3-CL 10.0 6 GGP-5-CL 8.0 7 PTXTP-4-6 10.0 Σ 100.0 Physicalproperties T (N, I) = 124.0° C. Δn (20° C., 589 nm) = N/A Δε (20°, 1kHz) = 2.7 γ₁ (20° C.) = 297 mPa · s k₁₁ (20° C.) = 17.4 pN k₃₃ (20° C.)= 26.4 pN

Mixture M-3 Composition Compound Concentration/ No. Abbreviation % byweight 1 CC-3-V 10.0 2 PP-1-2V1 7.0 3 PPTUI-3-2 20.0 4 PPTUI-3-4 30.0 5GGP-5-CL 20.0 6 PGUQU-5-F 3.0 7 PTXTP-4-6 10.0 Σ 100.0 Physicalproperties T (N, I) = 129.0° C. Δn (20° C., 589 nm) = N/A Δε (20°, 1kHz) = 4.0 γ₁ (20° C.) = 331 mPa · s k₁₁ (20° C.) = 17.8 pN k₃₃ (20° C.)= 24.7 pN

Mixture M-4 Composition Compound Concentration/ No. Abbreviation % byweight 1 PPTUI-3-2 20.0 2 PPTUI-3-4 30.0 3 GGP-3-CL 20.0 4 PGUQU-5-F 3.05 PTXTP-4-6 10.0 6 PTP(1)I-4-A1 17.0 Σ 100.0 Physical properties T (N,I) = 129.5° C. Δn (20° C., 589 nm) = N/A Δε (20°, 1 kHz) = 4.1 γ₁ (20°C.) = 632 mPa · s k₁₁ (20° C.) = 14.7 pN k₃₃ (20° C.) = 28.7 pN

All mixtures M1 to M4 are very well suitable for applications in themicrowave range, especially for phase shifters.

In the following table 2, examples 1.4 to 1.4 are shown in comparisonconcerning tuneability (τ), dielectric loss (tan δ_(ε) _(r,⊥) ) andmaterial quality (η).

TABLE 2 Example Mixture tan δ_(ε r,⊥) τ η (Ref.) RM-1 0.0125 0.2132 17.11.1 M-1 0.0126 0.2247 17.9 1.2 M-2 0.0125 0.2189 17.5 1.3 M-3 0.01290.2279 17.7 1.4 M-4 0.0127 0.2502 19.7

The comparison shows improved material quality η for all examples 1.1 to1.4 due to improved tuneabilities with the same or only slightly largerdielectric losses.

Examples 2.1-2.2

The following reference mixture (RM-2) and mixture examples M-5 and M-6are prepared and investigated.

Mixture RM-2 Composition Compound Concentration/ No. Abbreviation % byweight 1 PPTUI-3-2 10.0 2 PPTUI-3-4 15.0 2 PPTUI-4-4 30.0 3 PTP-3-5 14.04 PTP-4-5 14.0 5 PGUQU-3-F 2.0 6 PGUQU-5-F 3.0 7 CC-3-V 12.0 Σ 100.0Physical properties T (N, I) = 97.5° C. Δn (20° C., 589 nm) = 0.2652 Δε(20°, 1 kHz) = 2.1 γ₁ (20° C.) = 220 mPa · s k₁₁ (20° C.) = 13.5 pN k₃₃(20° C.) = 19.6 pN

Mixture M-5 Composition Compound Concentration/ No. Abbreviation % byweight 1 PPTUI-3-2 10.0 2 PPTUI-3-4 10.0 2 PPTUI-4-4 30.0 3 PTP-3-5 11.04 PTP-4-5 11.0 5 PGUQU-3-F 3.0 6 PGUQU-5-F 3.0 7 CC-3-V 12.0 8 PTXTP-4-610.0 Σ 100.0 Physical properties T (N, I) = N/A ° C. Δn (20° C., 589 nm)= N/A Δε (20°, 1 kHz) = 2.4 γ₁ (20° C.) = 382 mPa · s k₁₁ (20° C.) =14.4 pN k₃₃ (20° C.) = 21.1 pN

Mixture M-6 Composition Compound Concentration/ No. Abbreviation % byweight 1 PPTUI-3-2 10.0 2 PPTUI-3-4 10.0 2 PPTUI-4-4 30.0 3 PTP-3-5 11.04 PTP-4-5 11.0 5 PGUQU-3-F 2.0 6 PGUQU-5-F 2.0 7 PTXTP-4-6 10.0 8PTP(1)I-4-A1 14.0 Σ 100.0 Physical properties T (N, I) = N/A ° C. Δn(20° C., 589 nm) = N/A Δε (20°, 1 kHz) = 2.2 γ₁ (20° C.) = 393 mPa · sk₁₁ (20° C.) = 11.5 pN k₃₃ (20° C.) = 21.1 pN

Both mixtures M5 and M6 are very well suitable for applications in themicrowave range, especially for phase shifters.

In the following table 2, examples 2.1. and 2.2 are shown in comparisonwith the reference RM-2 concerning tunability (t), dielectric loss (tanδ_(ε) _(r,⊥) ) and material quality (η).

TABLE 2 Example Mixture tan δ_(ε r,⊥) τ η (Ref.) RM-2 0.0103 0.2060 20.01.1 M-5 0.0102 0.2122 20.7 1.2 M-6 0.0088 0.2317 26.3

The comparison shows improved material quality η for both examples 2.1and 2.2 due to improved tunabilities with lower dielectric losses.

Example 3.1

The following reference mixture (RM-3) and Mixture examples M-7 areprepared and investigated.

Mixture RM-3 Composition Compound Concentration/ No. Abbreviation % byweight 1 PTiNpTP-4-4 21.0 2 PTP(c3)TP-4-4 20.0 3 PTiNpTP-4-6 22.0 4PTP(1)I-4-A1 30.0 5 PTiNpTP-6-6 7.0 Σ 100.0 Physical properties T (N, I)= N/A Δn (20° C., 589 nm) = N/A Δε (20°, 1 kHz) = 2.2 γ₁ (20° C.) = 2136mPa · s k₁₁ (20° C.) = 11.5 pN k₃₃ (20° C.) = 21.1 pN tan δ_(ε r,⊥) =0.0054 τ = 0.2654 η= 48.9

Mixture M-7 Composition Compound Concentration/ No. Abbreviation % byweight 1 PTiNpTP-4-4 21.0 2 PTiNpTP-4-6 22.0 3 PTP(1)I-4-A1 35.0 4PTiNpTP-6-6 7.0 5 PTXTP-4-4 5.0 6 PTXTP-3-F 5.0 7 PTXTP-4-F 5.0 Σ 100.0Physical properties T (N, I) = N/A ° C. Δn (20° C., 589 nm) = N/A Δε(20°, 1 kHz) = 1.3 γ₁ (20° C.) = 1418 mPa · s k₁₁ (20° C.) = 11.4 pN k₃₃(20° C.) = 30.9 pN tan δ_(ε r,⊥) = 0.0058 τ = 0.278 η = 48.1

Mixtures M7 is very well suitable for applications in the microwaverange, especially for phase shifters.

The comparison of Mixture M-7 with Reference RM-3 shows similarproperties in terms of material quality but at the same time asignificantly reduced rotational viscosity.

The invention claimed is:
 1. A liquid-crystal medium, comprising one ormore compounds of formula A-2

wherein R⁰¹ denotes H, unfluorinated alkyl or unfluorinated alkoxyhaving 1 to 17 C atoms or unfluorinated alkenyl, unfluorinatedalkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, and X⁰¹denotes F, Cl, —NCS, —SF₅, fluorinated alkyl, fluorinated alkenyl orfluorinated alkoxy having 1 to 7 C atoms; and one or more compounds offormula II

wherein L²¹ denotes R²¹ and, in the case where Z²¹ and/or Z²² denotetrans-CH═CH— or trans-CF═CF—, alternatively denotes X²¹, L²² denotes R²²and, in the case where Z²¹ and/or Z²² denote trans-CH═CH— ortrans-CF═CF—, alternatively denotes X²², R²¹ and R²² independently ofone another, denote H, unfluorinated alkyl or unfluorinated alkoxyhaving 1 to 17 C atoms or unfluorinated alkenyl, unfluorinated alkynyl,unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 Catoms, X²¹ and X²² independently of one another, denote F, Cl, —CN,—NCS, —SF₅, fluorinated alkyl or alkoxy having 1 to 7 C atoms orfluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 7 C atoms, or—NCS, Z²¹ and Z²² denotes trans-CH═CH—, trans-CF═CF—, —C≡C— or a singlebond, with the proviso that at least one of Z²¹ and Z²² denotes —C≡C—,

 to

 independently of one another, denote

 and n denotes 0 or
 1. 2. The liquid-crystal medium according to claim1, additionally comprising one or more compounds of the formula I

wherein L¹¹ denotes R¹¹ or X¹¹, L¹² denotes R¹² or X¹², R¹¹ and R¹²independently of one another, denote H, unfluorinated alkyl orunfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl,unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 Catoms, X¹¹ and X¹² independently of one another, denote H, F, Cl, —CN,—NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to 7 Catoms or fluorinated alkenyl, unfluorinated or fluorinated alkenyloxy orunfluorinated or fluorinated alkoxyalkyl having 2 to 7 C atoms, and

 to

 independently of one another, denote


3. The liquid-crystal medium according to claim 2, wherein one or morecompounds of formula I are of formula I-1c

wherein Y¹¹ and Y¹² independently of one another, denote H or F, R¹¹denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinatedalkenyl having 2 to 7 C atoms, and X¹² denotes F, Cl or OCF₃.
 4. Theliquid-crystal medium according to claim 1, wherein one or morecompounds of formula II are of one or more compounds of formulae II-1 toII-6:

in which Z²¹ and Z²² denote trans-CH═CH— or trans-CF═CF—, R²¹ and R²²independently of one another, denote H, unfluorinated alkyl orunfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl,unfluorinated alkynyl, unfluorinated alkenyloxy or unfluorinatedalkoxyalkyl having 2 to 15 C atoms, X²² denotes F, Cl, —CN or —NCS, andand one of

 to

 denotes

and the others independently of each other denote

and where the compounds of formula II-3 are excluded from the compoundsof formula II-2.
 5. The liquid-crystal medium according to claim 1,wherein the total concentration of the one or more compounds of formulaA-2 in the medium is 1% to 30%.
 6. The liquid-crystal medium accordingto claim 1, wherein, in formula A-2, R⁰¹ denotes unfluorinated alkylwith 1 to 6 C atoms and X⁰¹ denotes F.
 7. The liquid-crystal mediumaccording to claim 1, wherein the total concentration of the one or morecompounds of the formula II in the medium is 30% to 99%.
 8. A componentfor high-frequency technology, comprising the liquid crystal mediumaccording to claim
 1. 9. The component according to claim 8, which issuitable for operation in the microwave range.
 10. The componentaccording to claim 8, which is a phase shifter.
 11. A process forpreparing the liquid-crystal medium according to claim 1, comprisingmixing one or more compounds of formula A-2 with one or more compoundsof formula II, and optionally with one or more further compounds and/orwith one or more additives.
 12. A microwave antenna array, comprisingone or more components according to claim
 8. 13. A compound of formulaA-2

wherein R⁰¹ denotes H, unfluorinated alkyl or unfluorinated alkoxyhaving 1 to 17 C atoms or unfluorinated alkenyl, unfluorinatedalkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, and X⁰¹denotes F, Cl, —NCS, —SF₅, fluorinated alkyl, fluorinated alkenyl orfluorinated alkoxy having 1 to 7 C atoms.
 14. The compound according toclaim 13, wherein X⁰¹ denotes F.
 15. The compound according to claim 13,wherein one or more compounds of formula A-2 are of one or morecompounds of formulae A-2a to A-2f


16. The compound according to claim 15, wherein one or more compounds offormula A-2 are of one or more compounds of formulae A-2c to A-2f. 17.The liquid-crystal medium according to claim 1, wherein, in formula A-2,X⁰¹ denotes F.
 18. The liquid-crystal medium according to claim 1,wherein, in formula A-2, X⁰¹ denotes unfluorinated alkyl with 3 to 6 Catoms and X⁰¹ denotes F.
 19. The liquid-crystal medium according toclaim 1, wherein the total concentration of the one or more compounds offormula A-2 in the medium is 5% to 20%.
 20. The liquid-crystal mediumaccording to claim 1, wherein the total concentration of the one or morecompounds of formula A-2 in the medium is 10 to 15%.